Existing ride height control systems for over the highway trucks and tractors control only the distance between a point on the suspension and the frame of the truck or tractor. As the vehicle load and operating conditions change, existing ride height control systems work only to maintain this distance. Since leaf springs of an air spring suspension deflect under load, maintaining the height of a specific point on the suspension does not maintain correct driveline angles. As a result, some driveline error is introduced when the vehicle is either loaded or unloaded. These driveline errors are responsible for vibrations in the driveline.
Flow characteristics of the ride height control system is partially responsible for the air consumption rate of the vehicle. The air consumption rate impacts the compressor life and fuel economy of the vehicle. Traditional mechanical ride height control systems compromise between accurately controlling the ride height and reducing the air consumption rate. In order to reduce air consumption, existing mechanical systems include a dead band of ride heights where the system does not react. The dead band allows the suspension ride height to vary from the initial setting by a specific amount before adjustments are made. Without a dead band in a mechanical system, dynamic road inputs would cause the system to constantly fill and exhaust air. The dead band reduces the responsiveness of the ride height control system.
There is a need for an electronic ride height control system that controls ride height based on vehicle loading to maintain proper driveline angles. There is also a need for an electronic ride height control system that has a reduced dead band.